Capturing and analyzing pattern diversity: an example using the melanistic spotted patterns of leopard geckos

Tilmann Glimm,Ylenia Chiari,Maria Kiskowski,Nickolas Moreno

doi:10.7717/peerj.11829

Tilmann Glimm, Ylenia Chiari + Show 2 more

Open Access

https://doi.org/10.7717/peerj.11829

Copy DOI

Abstract

Animal color patterns are widely studied in ecology, evolution, and through mathematical modeling. Patterns may vary among distinct body parts such as the head, trunk or tail. As large amounts of photographic data is becoming more easily available, there is a growing need for general quantitative methods for capturing and analyzing the full complexity and details of pattern variation. Detailed information on variation in color pattern elements is necessary to understand how patterns are produced and established during development, and which evolutionary forces may constrain such a variation. Here, we develop an approach to capture and analyze variation in melanistic color pattern elements in leopard geckos. We use this data to study the variation among different body parts of leopard geckos and to draw inferences about their development. We compare patterns using 14 different indices such as the ratio of melanistic versus total area, the ellipticity of spots, and the size of spots and use these to define a composite distance between two patterns. Pattern presence/absence among the different body parts indicates a clear pathway of pattern establishment from the head to the back legs. Together with weak within-individual correlation between leg patterns and main body patterns, this suggests that pattern establishment in the head and tail may be independent from the rest of the body. We found that patterns vary greatest in size and density of the spots among body parts and individuals, but little in their average shapes. We also found a correlation between the melanistic patterns of the two front legs, as well as the two back legs, and also between the head, tail and trunk, especially for the density and size of the spots, but not their shape or inter-spot distance. Our data collection and analysis approach can be applied to other organisms to study variation in color patterns between body parts and to address questions on pattern formation and establishment in animals.

Highlights

Animal color patterns vary within and among individuals, including variation among distinct body parts such as the head, trunk, tail, wings, or ventral or dorsal sides, possibly in response to different selection pressures
Our sample size is limited for the ‘‘lemon frost’’ morph, there appeared to be an effect of morphotype: for the ‘‘normal’’ morphotype, absence of patterns on the front legs always meant that the back legs were unpatterned, whereas this was reversed for this morph, since no gecko had patterned front legs
Similar approaches have been taken for giraffe coat patterns (Lee, Cavener & Bond, 2018) and salmonid fish skin patterns (Miyazawa, Kondo & Okamoto, 2010); in our work, we captured different aspects of pattern elements and looked at variation for each of the elements, and we used two concepts of distances to quantify the degree of similarity of patterns as whole

Summary

Introduction

Animal color patterns vary within and among individuals, including variation among distinct body parts such as the head, trunk, tail, wings, or ventral or dorsal sides, possibly in response to different selection pressures Variation in color pattern is considered a classical example of an adaptive trait, as it is often involved in communication among conspecifics, intrasexual competition, and antipredator functions (Caro, 2005; Gomez, Théry & Losos, 2007; Tibbetts & Dale, 2004; Solan et al, 2019)

Objectives

Methods

Results

Conclusion